1. Field of the Invention
This invention relates to the purification and distribution of process chemical gases to an end user, in particular, the purification and distribution of ultrapure electronic specialty gases to semiconductor wafer and chip processing tools.
2. Description of the Related Art
In semiconductor manufacturing industry, many different high purity chemical gases are needed for etching, deposition, and surface cleaning. A partial list of such chemical gases includes ammonia (NH3), hydrogen chloride (HCl), hydrogen bromide (HBr), nitrous oxide (N2O), sulfur hexafluoride (SF6), carbon dioxide (CO2), hydrogen fluoride (HF), fluoromethane (CH3F), hexafluoroethane (C2F6), tungsten hexafluoride (WF6), chlorine (Cl2), boron trichloride (BCl3), perfluoro-propane(C3F8), trifluorochloro-methane(ClF3), dichlorosilane (SiH2Cl2), disilane (Si2H6), trichlorosilane (SiHCl3), silane tetrachlorosilane (SiCl4) etc.
A known method of distributing these gases is to have the gases flow through a distribution system under their vapor pressure from the source to the user stations. Systems and methods for controlled delivery of liquefied gases are further discussed in U.S. Pat. No. 5,761,911 and U.S. Ser. No. 08/893,499, which are incorporated herein by reference in their entirety.
Many of the chemicals employed in the semiconductor manufacturing processes, while introduced to the processing tools in the gaseous state, are stored as liquids in gas cylinders under their own respective vapor pressures. The cylinders with a typical volume of less than about 50 liters are usually housed within gas cabinets.
A single gas cabinet typically supplies the chemical vapor to a single or at most several semiconductor processing tools. Operation of the gas cabinets and the cylinders housed therein can be hazardous, labor intensive and costly activity. As the chemical is depleted, it is imperative that the gas cylinder can be replaced with careful and proper handling procedures.
In order to reduce the total number of gas cabinets required in the semiconductor manufacturing facility, it has recently been proposed that a single gas cabinet service multiple processing tools. Since the volumes of the cylinders housed in the gas cabinets do not increase with the number of processing tools being serviced, replacement frequency of the cylinder cabinets necessarily increases. It is, however, desirable to minimize the frequency of cylinder replacement not only for safety concerns but also to reduce the risk of introducing impurities that may cause significant product loss.
In addition, the vapor pressure of a chemical gas is strongly dependent on temperature and, therefore, the attainable flow varies upon changes in ambient temperature. As a result, it is difficult to maintain a desired flow rate to meet the user""s needs. For some of the chemicals, the vapor pressures are not high enough to have the gas flow to a remote locale even at high ambient temperatures. Heat may be supplied to the source to keep the temperature within an acceptable range. Nonetheless, even by maintaining the temperatures within a predetermined range the gas purity is not assured because liquid droplets with impurities become entrained in the gas during a non-stable evaporation inside the bulk container.
To meet the requirements of the semiconductor processing industry and to overcome the disadvantages of the related art, it is an object of the present invention to provide a novel system for gas purification and distribution with ease of operation and control.
It is another object of the invention to fully vaporize and purify gases.
It is a further object of the invention to provide a flexible system needed to accommodate various gases and their delivery to the point of use in a quick and facile manner.
It is yet another object of the invention to provide a compact system accommodated in a limited space, wherein the system can be operated in close proximity to the users.
Other objects and aspects of the present invention will become apparent to one of ordinary skill in the art upon review of the specification, drawings and claims appended hereto.
According to a first aspect of the present invention, a novel distribution system for ultrapure chemical gases to the point of use at a semiconductor processing facility is provided. The system includes a liquefied gas source, a vaporization purification device, and, a buffer tank. The liquefied gas source is in communication with the vaporization purification device to provide a liquefied gas to the bed. An ultrapure chemical gas is generated in the vapor purification bed, and the vapor is routed to a buffer tank and further to a point of use from the buffer tank.
According to a further aspect of the invention, a system for vaporizing and purifying a gas is provided. The system includes a supply tank, wherein a chemical gas is disposed. The supply tank is connected to a temperature containment chamber having at least one vaporization purification bed therein and a buffer tank disposed downstream of said temperature containment chamber.
According to yet another aspect of the invention, a vaporization and purification device system is provided. The system includes a tubular main body having a first and a second end. The first end includes a nozzle connected thereto, wherein a liquid chemical is introduced at a pressure higher than the pressure within the tubular main body to vaporize and purify the chemical. The system further includes a second end having a three-way connector attached thereto.
According to a further aspect of the invention, a method for providing ultrapure chemical gases to the point of use at a semiconductor processing facility is provided. The method includes supplying a chemical gas to a containment chamber having at least one vaporization and purification device therein. The chemical gas in the containment chamber is vaporized and purified by passing the chemical gas through at least one vaporization and purification device. The light impurities are eliminated through a pressure relief valve disposed at a top end of the containment chamber. Thereafter, the ultrapure chemical generated is routed to a buffer tank and distributed to a point of use.
Thus, in accordance with the inventive system chemical gases are vaporized, purified and delivered to a point of use in an ultra-pure form in a quick and facile manner.